Computer systems typically output visual information to display screens such as cathode ray tube (CRT) monitors or liquid crystal displays (LCDs). A display is made up of a grid of picture elements, or pixels, each of which has a color value associated with it. This grid of pixels is a two-dimensional rectangular grid along an x-axis and a y-axis. A graphical image is a set of pixels that has a dimensions (typically a height and a width), expressed in pixels, and locations and color values for each of those pixels. A graphical image may be stored in a file (or other data structure) and be displayed in whole or in part on a subset of or the whole display screen.
Imaging software, such as Photoshop® by Adobe Systems Incorporated of San Jose, Calif., is a type of software used to view or manipulate graphical images. Imaging software is typically presented in a windowed graphical user interface (GUI) environment on a computer system display. Imaging software displays a graphical image that can then be manipulated by a user. Some types of manipulations that a user may perform include transformations such as panning the image (if the image is too large to display on the display screen), zooming in to and out of the image, and rotating the image.
Imaging software may display an image within a window on the display. Oftentimes the window includes rulers along its edges to allow a user to determine how large the image is and where certain features are located within the image. The rulers can be especially useful when the image is zoomed and the entire image is not visible.
Some users rotate an image when manipulating it to ease manipulation. For example, some users prefer to align the image they are working on with their elbow to improve their ability to create or modify the image. When the image is rotated in this fashion, the user is unable to use rulers on the edge of the image window, because the rotated image is no longer aligned with the edges of the window. Additionally, when the image is zoomed in, the user is unable to determine the location of features within the image.
Thus, what is needed is a ruler without the limitations of conventional techniques.